Blade Runner: Double Amputee, Oscar Pistorius, Competes for South Africa at the World Track and Field Championships

Oscar Pistorius is many things: a global inspiration, a motivational speaker and a champion of the disadvantaged. But he is most complete when he tears around the track as fast as any man alive -- more remarkable because he is a double amputee.

"I was born with missing fibula, which is one of the bones between your knee and your ankle," said Pistorius. "At 11-months- old, my parents decided to have my legs amputated."

Pistorius learned to walk on prosthetics, and while it was still a challenge he learned to run -- and then to run fast, real fast. So fast that he fought to compete against able-bodied athletes even though some believed his prosthetics gave him an advantage.

"The legs are not giving me an unfair advantage," Pistorius, who hopes to compete in both the Olympics and the Paralympics in London next summer, told ABC News. "If they can prove that they give me an advantage, then I won't run anymore."

In 2008, track's governing body voted to allow Pistorius to compete against anyone, and last month he qualified for the Track and Field World Championships being held this week in South Korea.

On Thursday he ran the leadoff leg of the 4x400-meter relay semi-final, and not only did his team, South Africa, win a surprising birth in the final, it broke a South African record.

But the victory wasn't good enough for Pistorius. With five runners vying for the four spots in the final relay, the team decided that the slowest of the five would be replaced. That runner was Pistorius.

He was devastated and tweeted: "Haven't Been included in the Final for the SA Mens 4x400m. Pretty Guttered."

South Africa would finish second in the final, which meant a historic silver medal for Pistorius, because he ran in the qualifying race. Still the athlete in Pistorius will never be satisfied knowing he didn't run when it mattered most. Which, when you think about it, might just be progress. Pistorius was treated as so many disadvantaged dream to be, as just another athlete -- not as a mascot, not as a sideshow. And while he was disappointed, he wasn't bitter.

"It's been a great experience coming out here," he said. "I've gained many memories that will stay with me for the rest of my sporting and natural life. Its just been a big blessing."